Light beams or optical signals are frequently used to transmit digital data between electronic devices, both over long distances and between adjacent circuit boards. A light beam may be modulated as needed to carry data. An optical signal may also be used for other purposes including position or motion sensing, measurement, etc.
Consequently, optical technology plays a significant role in modern electronics, and many electronic devices employ optical components. Examples of such optical components include optical or light sources such as light emitting diodes and lasers, waveguides, fiber optics, lenses and other optics, photo-detectors and other optical sensors, optically-sensitive semiconductors, and others.
In some optical applications, optical waveguides are used together with electrical currents to accomplish desired tasks. For example, in waveguide modulators, an electronic signal modulates the index of refraction of the waveguide material, either through the electro-optic effect or through charge injection, imparting a phase or amplitude modulation on the optical signal, depending on the waveguide configuration. As another example, optical detectors integrated into waveguides can output an electrical signal representative of an optical signal present in the waveguide. Such waveguide devices require an electrical connection to at least one electrical contact, where charge may be selectively injected, removed, or measured.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.